1. Field
The present specification describes a reversible fuel cell oxygen electrode, a reversible fuel cell including the same, and a method for preparing the same.
[Description about Government-Sponsored Research and Development]
This research was supervised by the Korea Institute of Science and Technology, and sponsored by the Ministry of Science, ICT and Future Planning of Korea. The project name was “Development of Innovative technology regarding electrolysis of CO2 at a low temperature for producing synthesis gas” (project number: 1711027334). This research was also supervised by the Korea Institute of Science and Technology, and sponsored by the Ministry of Trade, Industry and Energy of Korea. The project name was “Development of source technology regarding non-platinum catalyst for reducing the price of fuel cells for automobiles” (project number: 20133010011320).
2. Description of the Related Art
As a means for replacing an existing system based on fossil fuels, renewable energy resources such as solar light or wind power have attracted much attention. The production of electric power by these renewable energy sources greatly depends on the weather or an energy storage system (ESS) capable of storing an additional electric power, and the like.
A reversible fuel cell or regenerative fuel cell (hereinafter referred to as RFC) enables bidirectional conversion between electricity and hydrogen, and has been considered as a promising candidate for electrochemical energy storage. Since an energy capacity of a system based on the RFC may be increased regardless of electric power, capital costs for expanding the energy capacity are lower than those of lithium batteries. Accordingly, the RFC is expected to be suitable for being applied to large capacity systems.
RFCs are classified into RFCs in which a fuel cell and a water electrolysis device are integrated (unitized regenerative fuel cells, hereinafter referred to as URFC) and RFCs in which a fuel cell and a water electrolysis device are separated (discrete regenerative fuel cells, hereinafter referred to as DRFC).
The DRFC can use commercially available fuel cells or water electrolysis devices, and thus, the technical entry barrier thereof is low, whereas the URFC has integrated fuel cells and water electrolysis devices, and thus, the technical entry barrier thereof is relatively high, but it is considered that capital costs due to the integration can be decreased.
However, a large loading amount of a noble metal electrochemical catalyst is generally required for the URFC in the related art, and there is a problem in that the system costs are increased for this reason. Since the oxygen reduction reaction [hereinafter referred to as ORR] and the oxygen evolution reaction [hereinafter referred to as OER] are slow, an electrochemical catalyst of platinum (Pt) and iridium (Ir) or iridium oxide (IrO2) has been together with the URFC, and for example, Pt—Ir alloys or (RuO2—IrO2)/Pt catalysts have been studied.
Since the content of the noble metal catalyst is high in these studies, attempts for lowering the content of the noble metal catalyst have been made. However, the water electrolysis and fuel cell performance of the RFC have been at an unsatisfactory level, and a high content of the noble metal catalyst is still required.